Evaluation of the Role of Fractures as the Major Water-conducting Features in Neogene Sedimentary Rocks

Abstract

Ke ywo r d s ：新第三紀堆積岩 n e o g e n es e d i me n t a r yr o c k s ， 割れ目の開口性 f r a c t u r ea p e r t u r e ， 割れ目の連続性・ 連結性 f r a c t u r ei n t e r c o n n e c t i v i t y ， 水みち wa t e r c o n d u c t i n gf e a t u r e ＊ （独） 日本原子力研究開発機構地層処分研究開発部門 J a p a n At o mi cEn e r g yAg e n c y , Ge o l o g i c a l I s o l a t i o nRe s e a r c ha n dDe v e l o p me n tDi r e c t o r a t e （会員） m，2 7 2 . 6 ～2 7 4 . 6 m，2 8 7 . 1 ～2 8 9 . 1 m，3 2 0 . 9 ～3 2 2 . 9 m，3 6 2 . 2 ～3 6 4 . 2 m，3 9 7 . 7 ～3 9 9 . 7 mでは，F P に剪断割れ目と引張割 れ目の両者が認められた．いずれのF P においても認めら 6 ） GENTER, A. , C AS TAI NG, C . , DEZ AYES , C . , TENZ E R, H. , TRAI NEAU, H. a n dVI L L E MI N, T. （1 9 9 7 ） ：C o mp a r a t i v e a n a l y s i so fd i r e c t （c o r e ）a n di n d i r e c t （b o r e h o l ei ma g i n g t o o l s ）c o l l e c t i o n o ff r a c t u r ed a t ai n t h eHo tDr y Ro c k S o u l t z r e s e r v o i r（F r a n c e ） , J o u r n a l o f G e o p h y s i c a lRe s e a r c h , Vo l . 1 0 2 , p p . 1 5 4 1 9 1 5 4 3 1 .7 ） HAMM, S Y. , KI M, M. , C HEONG, J Y. , KI M, J Y. , S ON, M. a n dKI M, T W. （2 0 0 7 ） ：Re l a t i o n s h i pb e t we e nh y d r a u l i c c o n d u c t i v i t y a n d f r a c t u r e p r o p e r t i e s e s t i ma t e d f r o m p a c k e rt e s t sa n d b o r e h o l ed a t ai n af r a c t u r e d g r a n i t e , E n g i n e e r i n gGe o l o g y , Vo l . 9 2 , p p . 7 3 8 7 .8 ） TS ANG, C F . , HUFS C HMEI D, P . a n dHAL E , F . V. （1 9 9 0 ） ： De t e r mi n a t i o n o f f r a c t u r e i n f l o w p a r a me t e r s wi t h a

The relationships among brittleness, deformation behavior, and transport properties in mudstones: An example from the Horonobe Underground Research Laboratory, Japan

“…The chronology of fault formation can be estimated from their orientations. The most common orientations of faults are the same in both the Wakkanai and Koetoi formations, nearly perpendicular to bedding planes in the Wakkanai Formation [ Funaki et al , 2009]. Because bedding planes have different orientations from borehole to borehole, they were rotated into the horizontal plane to enable an analysis of the fault orientations.…”

“…Previous studies, using geophysical and fluid logging techniques, and in situ hydraulic tests, showed that the Koetoi Formation is a hydrogeologically porous medium because of its poor connectivity and the closing of fractures, while the Wakkanai Formation has, in part, the hydrogeological properties of a fractured medium, because of moderate connectivity and the opening of fractures [ Kurikami et al , 2008; Funaki et al , 2009]. In this study, mudstones having a log K i‐packer / K i‐lab <3 are assumed to behave hydrogeologically as porous media, while those with a log K i‐packer / K i‐lab >3 are assumed to have the hydrogeological properties of fractured media.…”

“…Tectonic deformation structures, such as compactional shear bands (i.e., shear bands with volumetric compaction), faults, and joints, are observed in outcrops and in drill cores from the Wakkanai and Koetoi formations [ Funaki et al , 2009; Ishii et al , 2010; E. Ishii, Microstructure and origin of faults in siliceous mudstone at the Horonobe Underground Research Laboratory site, Japan, submitted to Journal of Structural Geology , 2011]. However, they are seldom observed in the Yuchi Formation.…”

“…However, even where the bands are very thin, their presence is indicated by darkish planes on the faults (Figures 3b and 5c). Fault breccia and/or fault gouge are associated with some of the faults [ Funaki et al , 2009; Ishii et al , 2010]. …”

Influence of a fault system on rock mass response to shaft excavation in soft sedimentary rock, Horonobe area, northern Japan

“…Fractures in the Koetoi Formation consist of many faults and few tension fractures [19]. The fault length is generally about 1 m [20] (Fig.…”